Relationships Among Organisms

While grazing, a buffalo stirs up mosquitos. These mosquitos are eaten by egrets. What type of relationship does the egret have with the buffalo?

• mutualism

• commensalism

• parasitism

• predation

Two interactions are predation and parasitism. In predation, predators feed on prey. In parasitism, parasites depend on host organisms. Which correctly describes the relative number of organisms in parasitism or predation?

• The number of parasites is usually greater than the number of host organisms.

• The number of predators is usually greater than the number of prey.

• The number of parasites is always equal to the number of host organisms.

• The number of predators is always equal to the number of prey.

Lisa is watching honeybees in her garden. Her mom explains that bees are helping the flowers to reproduce and in return, bees are gathering the plants' nectar for food. What type of interaction do the honeybees and the flowers show in the garden?

• mutualism

• commensalism

• parasitism

• predation

An eagle and a bear both feed on the same species of salmon in the same location. What type of relationship is displayed by the eagle and the bear?

• competition

• commensalism

• predation

• parasitism

Researchers argue that some bacteria in the human gut are in a symbiotic relationship with humans, called mutualism. Which observation is consistent with this argument?

• Disease in humans is not caused by bacteria.

• The same nutrients are used by bacteria and humans.

• Bacteria increase the risk of cancer in humans.

• Bacteria provide vitamins to humans.

Mutualism is a long lasting, mutually beneficial interaction between organisms. Which relationship best reflects mutualism.

• Botfly larvae lay their eggs on jaguars and consume blood and nutrients from the jaguars.

• Galapagos tortoises eat all the branches of cactus plants; the plant is harmed and sometimes dies.

• A starfish provides a safe place for sea worms to reside; the starfish receives nothing in return.

• Reef corals build a hard protective skeleton that algae live in; the algae provide energy for the coral through photosynthesis.

Sticklebacks that harbor a tapeworm are less likely to perform courtship behavior correctly and are less successful at reproducing. The tapeworm's relationship to sticklebacks can be classified as which of the following?

• competition

• mutualism

• commensalism

• parasitism

Thomas's dog has fleas. The fleas live by feeding on the dog's blood. Meanwhile, the dog is constantly scratching and does not feel well. The relationship between the fleas and the dog can be classified as which of the following?

• commsalism

• mutualism

• parasitism

• predation

Which type of symbiotic relationship occurs when ecological niches overlap and multiple organisms seek the same resources?

• commensalism

• predation

• parasitism

• competition

The graph above shows changes in the population of a predator and its prey over time.

Which best explains the increases and decreases in the predator population?

• Predators migrate frequently.

• There were variations in the food supply.

• The paramecium competed with the yeast.

• Populations always achieve a stable level.